Rheostat



H- N. WADE RHEOSTAT Filed July 1, 1918 will UNITED STATES Patented Aug. 14, 1923.

Emm N, WADELOF MILWAUKEE; isconsin, AssIGNon To This CUT ER-HAMM R ramps 00., or MILWAUKEE, 'WISCONSIN, A conronn'rron or WISCONSIN;

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Be it known tliet I, Wennh citizen of the United State's, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, li' ayeinv'entediriew and useful linproveinents iii Rheostats, of which the following is a 1111, near, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification. H This invention relates to, rheos t ats more particularly to theseof the fiui'd ty'pe. I In practice such rheostats are'frequently desired for alternating current systems nihereinit is importantt'o provide for 'gr'ad- .ual resistance veriations between wide limits and or preservation of phase ba'l tim a 0n, the ether 'liand, inu'eh "di fli'culty has been experiencedin producing afluid rheostat affording such c'ontrol fefifortsin this direction havingle dto complicated and costly structures, andth'e' present invention has among its 'objects'to provide a simple and eflicient fluid rheostat to meet such req i e ent?- I it a A urther object is to provide a fiuid rlie'os stat wherein the electrodes are ffixe'dly' mounted. and tlie fluid is raised or lowered with respect thereto in a manner greatly to sirnblifythe control means required and to facilitate automatic "regulation thereof.-

A further object is, to provide a fluid rheostat wherein the height of the 'fl uid maybe regulated by air pressure and Where in. the supply of air rnay be utilized to eflectcirculation of fluid between the electrodes. r ,j Other objects and advantages ill'herein after appear. H V

.-.In the accompanying drawing wherein is illustrated an embodiment of the invention, Figure 1 is a sideelev'ational View, partly in section, of the rheostat, the control means therefore being schematically and diagrammaticallyillustrated; While,

I Fig; 2 is a similar end yiew'of the rheo stat.

I Referring to the drawing, the same; Shows a rheostat arranged to control a three phase alternating current circuit a, b, c, and comprising three sets oft elec rodes f, extending downwardly to different levels ing furthermoregradually tapered "and the i918. "Serial in). 242,712.

within an electrolyte m1; 6 and fixed with its tions, the electrodes d being longest and be:

eitre ne lcWer endstherebjifbeing extended to provide reducedls'urfaces (Z for uninter r'upted contact w th the electrolyte. The

'electro'clesf are relatively short, their lower ends bein'gflnore bluntly tapered, Whereas,

the'electrod'e's e are similar to the electrodes f of a length intermediate of the elecd aild f;

The aforesaid setsof electrodes are syminetric'ally arranged according to length,

and eq'ually, spaced from one another; That to say,;'the electrodes 22 arearranged at equal intervals. I The electrodes 2 are ar- "ranged midway between adjacent electrodes,

21 [While the electrodes f are similarly arr an-ged inidwaybetween adjacent electrodes I, The several 'eleetredes' are connected to the respective conductors (t, cfof the coin troll' l circuit :in r a definite sequenfce which asf'olloits; Beginning at the of Fig. I, the 'firstfele'ctrede is bnne'cted "to cop ductor c, the second to a, the third to b, the

'fourthto 0 and thence on in the same 'order. 7 By thisarrang'ement each of the phase conductors a, b and 0V is connected to the [same number of: electrodes of each length, whereby the effective electrode area is all conditions immersiomthe first and last electrodes "of the series being for this purpose regarded asone, since their outer surfaces are electrically inective whereby the1r;co nb1neld effective areas exactlyequal equally apportioned ainongthe phases'und'er 1;;

paths of'equal length is all times rovided between all phases of the tent-m led circuit whereas. upon predetermined rises level ofthe electrolyte the length o'f each path is reduced by helf and the nurnber, of

paths is increased tv to 'fold while the efifeei tive electrode area is also increased. Obviously a drop in the electrolyte level produces similar effects but in an opposite sense while the taperv of the'lower ends of the electrodes 6 and f insures a smooth resistance variation during the aforesaid transformations.

For mounting the electrodes fixedly in the relation described, said electrodes are preterably provided adjacenttheir upper ends with three triangular-1y arranged openings T through which extend a like number of parallel rods 8 said rods being arranged above and longitudinally of the tank and bein g terminally supported by a pair oi blocks 9 of wood or other suitable material which are fixed across the tank adjacent its ends. The electrodes are provided with annular insulating supports 10 which are interposed between adjacent electrodes and are ot suita'blethickness to provide the necessary spacing thcrel'ietween. Each of said supports is provided. with a pair of oppositely arranged annular flanges 11. which are of materially greater diameter than the rods and are adapted to fit snugly within the openings 7 in the electrodes whereby said electrodes are supported in spaced and insulated relation to the rods and to each other.

To provide for varying the height of the electrolyte pneumatically, the tank 6 which is preferably rectangular in cross section is provided with a displacement chamber 12 located below the main electrolyte chamber 13 and formed by a pair of abutting interior walls 14 and 15. The former wall extends horizontally and is located an appreciable distance below the electrodes while the latter wall extends from the inner end of the wall 1st downwardly adjacent the side of the tank and terminates a short distance above the bottom thereof, thus providing an elongated port 16 and a passage 16" between said chambers.

Compressed air from a continuously acting pump 1.? or otli 2r suitable source supplied to the displacement chamber through a conduit 18, the supply of air to said chamber being regulable by means of a throttling valve 19 and being controllable selectively through a manually actuable valve 20 and an clectro-responsive valve said last urentioned valve being biased to closed position by gravity or otherwise and having an actuating winding 22 to be energized from asuitable current source Z, Z through a. manually operable switch 23.

The throttle valve 19 is located in the con duit 18 preferably adjacent the pump 1'? and is adapted to be set in a lixed position for regulating the rate of air admission to the displacement chamber 12. The manually operable valve 20 is located in abranch or by-pa conduit 24: connecting tliecmiduit 8 with the intake of the pump. The electroresponsive valve 21 is located in a valve chamber 25 which is in open communication with the conduit l8 wnile the discharge port of said valve is connected by a pipe 26 with the by-pass conduit 2 L, said latter conduit being furthermore provided with a pipe 2? connecting the same with the interior of the electrolyte tank above the highest level of electrolyte therein. The top 01 said tank is furthermore enclosed by means of a cover 28.

Each of the valves 20 and2l isoit suliicient capacity when fully open to permit passage of an appreciably greater volume of air than that supplied by the pump whereby upon opening Oit either of said valves air escapes from the displacement chamber for decreasing the immersion. of the electrodes while the ill air supplied by the pump is bypassed through the conduit 24 without entering said chamber. Obviously by varying the degree oi opening ofthe valve 20 or by intermittent openin and closing of the valve 21 the rate of increase or decrease in immersion oi the electrodes may be finely adjusted. Furthermore by means of the construction described, the air escaping from the displacement chamber through the valves 20 and 21 is returned to the pump through the by-pass 2i and thereafter reconducted to said chamber, while any air escaping within the main electrolyte chamber 13 is collected beneath the cover 28 and similarly returned to the pumping system through the conduit 2. whereby the air is used repeatedly and the electrolyte vapor suspended therein is conserved.

For cooling the electrolyte the usual cooling coils 29 are arranged within the tank adjacent the electrodes and a further set of cooling coils 30 is arranged immediately below the electrodes tlor absorbinp the heat generated while the electrolyte occupies only the lower levels and is therefore not eli'ectively cooled by the coils 29.

For causing circulation at the electrolyte and facilitating cooling thereof by said coils, a plurality of reduced openings Ell are provided in the wall let preterably adjacent its junction with the wall 15 whereby compressed air escapes lrom the displacement chamber in the form of bubbles which rise to the surface thus inducing a flow of elec trolyte between the electrodes and against the cooling coils. Also, following expulsion of the electrolyte from the displacement chamber, the thereafter supplied to said chamber by the pump escapes through the port 16 and the passage 16 for further increasin the circulation of the electrolyte. The pas are 16 and the line of o ienings 31 being arranged at right angles to the planes of the electrodes described. the incur-ed flow of electrolytes will be chiefly between and parallel to the electrode surt'aces wherel y the .ost ellicient circulation is obtained.

Whh; the a loredcscribed rheostat is ill) capableoit general application, the same is particularly adapted'to control-the motor secondary resistance of a motorv generator set such as that illustrated schematically inFig; 1. l V

7 As there illustrated,ythe lin'es'a, b, 0 controlled by the rheostat;areconnected in the rotor circuit ofa three phase induction motor 32 coupled to a gcnerator' 33-a-nd provided with an energy'storing fly-WheeL-said motor being s'uppliedwith primary current from lines L L L9. The rheostat is thus adapt ed to, provide secondary current regulation both underfstarting and running conditions of themotor. Furthermore during running it 'isdesirab'le to reduce the motor speed automatically by increasing the resistance of its secondary circuitu'pon on increase in load thereby permitting-the fly-wheel to as sume its proper share of such lncrement.

v For thispurpose the energizing circuit of "provide for responseand release thereof with consequent opening and closing of the valve 21 atany desired degree of current vanation the motor primary circuit, whereby the .rheostat resistance is automatically regulated according to varying load conditionsof the motor While manual control of the motor by means of the rheostat is also provided. i V 1 lVhat I claim" as new and desire to secure by Letters Patent is:

1. In a fluid 'rheostat, the COHlbiIlfltlOH cwith'anelectrolyte'ta-nk, of a plurality of electrodes extending difl'erent distances 'therewithin, said electrodes being arranged and connected in circuitto provide for increase in the number anddecr'ease in length of the current paths 'therebetween upon variation in the vertical relation of the electrolyte thereto. a

under" all conditions.

QQIna fluid rl1eostat,-the combination with an electrolyte "tank, of a. plurality of: electrodes extending different distances therein and. adapted to coact'ivi'th the electrolyteftovarythe resistance ofa polyphase circuit, said electrodes beingso arranged and so connectech'to said circuitas 'to provide a like number of current paths I of equal l'engthzbet ween the phases of said circuit In a" fluid rheostat, the 'combination Nit-h an electrolyte tank; of a" plurality of electrodes, extending different distances thereinand adapted to coact withthe electrolyte to vary the resistance of a polyphase circuit, said electrodes being so arranged and soconnected to said circuiteas to provide a like number of current ipaths'o'f equal length between the phases of said circuit under all conditions and to provide for increase in the number of said paths upon given variations in height of said elect-rolyte. '1

" 4.1n a fluid rheost-at, -the combination with an electrolyte tank, of :a plurality I of electrodes extending different distances therein andada-pted to coact with the electrolyte to vary theresistance of a polyphase circuit, said electrodes being so arranged and so connected to said circuit as to provide a like number of currentpaths of equal length between the phases of said circuit a under all conditions and to provide for increase in the number and decrease in length of said paths upon given variations in height of said electrolyte.

5. In a fluid rheostat the combination with an electrolyte tank, of a'plurality of electrodes extending therein and adapted to coact with the electrolyte to vary the resistance of a polyphase circuit, "said electrodes being so 1 arranged and so connected to said circuit as to provide a like number of current paths of equal length between the phases of said circuit underall conditions, and to provide for doubling the number and halving the length of said paths upon a given variation in height of said electrolyte. a

6. "Ina fluid rheostat, the combination with an electrolyte tank, of a plurality. of electrodes j extending different therein'and adaptedto coact with the electrolyte to vary the resistance'of a polyphase circuity said electrodespbeing so arranged and so connected to said circuit as to' provide 'a like number of current paths'of equal length betweenthe phases of said circuit under all conditions, andto provide for doubling the number and halving the length ofsaid paths repeatedly upon given consecutive variations in level of said electrolyte.

'Zfln a fluid rheostat, the combination with an electrolyte "tank, of a plurality of electrodes projecting' different distances there'wit'hin and adapted to coact with'the electrolyte for controlling the resistance of a polyphase circuit, adjacent electrodes "being connected to successive phase conductors ofisaid circuit and said electrodes being symmetrically arranged. according to their respective degrees of projection within said tank, x I a 8.; In a fluid rheostat, the combination with an electrolyte tank. of, a plurality of different distances I distances ot the electrolyte to make contact therewith in distinct steps, the electrodes constituting the lirst stop being equally spaced from one another, the electrodes of the second step being medially interposed between adjacent electrodes of the first step and the electrodes of the third step being similarly arranged between adjacent electrodes of the two former steps. 7

9. In a fluid rheostat, the combination with an electrolyte tank. of a plurality of electrodes extending unlike distances there within and adapted upon rise in level of the electrolyte to make contact'therewith and to be immersed therein in distinct steps, the longest electrodes constituting the first step being equally spaced from. one another, the electrodes next in length constituting the second step and being medially interposed between adjacent electrodes of the first step I and the shortest electrodes constituting: the

third step and being similarly arranged be tween adjacent electrodes of the former two steps.

10. In a fluid rhcostat, the combination with an electrolyte tank, of: a plurality of electrodes extending unlike distances therewithin and adapted upon rise in level of the electrolyte to make contact therewith and be immersed therein in distinct steps for varying the resistance 01. a polyphase circuit, the electrodes constituting the first step being equally spaced from one another within the tank, the electrodes of the second step being medially interposed between adjacent electrodes of the first step and the electrodes of the third step being similarly arranged between adjacent electrodes of the former two steps and adjacent electrodes bein r connected to successive phase conductors of said circuit whereby the total resistance is equally apportioned among the phases of the controlled circuit under all conditions of immersion of said electrodes.

11. In a fluid rheostat, the combination with an electrolyte tank, of a plurality of electrodes proj ecting therewithin and adapted to vary the resistance of the rheostat upon variation in height of the electrolyte, said tank having a displacement chamber located below said electrodes and in communication. with the space thereabout and means for introducing gas under pressure to said displacement chamber for varying'the height of electrolyte about said electrodes.

12. In a fluid rhcostatathe combination with an electrolyte tank of a plurality of electrodes extending therewithin for c0- action. with the electrolyte, said tank having a chamber located below said electrodes, and means for supplying compressed air to said chamber continuously, said chamber having restricted openings providing for escape of: air therefrom for causing circulation of electrolyte about said electrodes.

18. In a. fluid rheostat, the combination withan electrolyte tank, of a plurality of electrodes extending therewithin for c0- acting with the electrolyte, said tank having a chamber located below said electrodes, and means for supplying compressed air to said chamber, the latter having a plurality of reduced openings located laterally of said electrodes and providing for a continuous escape of air therethrough for causing circulation of the electrolyte between and across said electrodes.

14. In a fluid rheostat, the combination with an electrolyte tank, of a plurality of electrodes extending therewithin tor coa-ction with the electrolyte, said tank having a dis placement chamber located below said electrodes and having a port communicating with the interior of said tank, means for supplying compressed air to said chamber to expel electrolyte therefrom for varying the immersion of aid electrodes, said chamber having a plurality of reduced openings providing a continuous escape of air upwardly within said tank for inducing circulation of the electrolyte about said electrodes.

15. In a fluid rheostat, the combination with an electrolyte tank, of a plurality of electrodes extending therewithin for coaction with the electrolyte, said tank having a displacement chamber located below said electrodes and having a port located near its bottom and laterally of the several electrodes for providing communication with the interior of said. tank, and means for supplying compressed air to said chamber and exhausting air therefrom for varying the distribution of the electrolyte within said chamher and. said tank to vary the immersion of said. electrodes, said port being adapted under given conditions to provide for escape of air upwardly within said tank for inducing circulation of the electrolyte between and across said electrodes.

16. In a fluid rheostat, the combination with an electrolyte tank provided with an interiorly located displacement chamber in open communication therewith, of a plurality of electrodes extending downwardly within said tank above said chamber for coaction with the electrolyte, a continuously acting pump for supplying compressed air to said chamber to expel electrolyte therefrom for varying the immersion of said electrodes, and means for collecting any air escaping from'said tank together with the electrolyte vapor suspended therein and conducting the same to the intake of said pump to be returned to said chamber thereby.

17. In a fluid. rheostat, the combination with an electrolyte tank, of a plurality of electrodes adapted to co-operate with the electrolyte therein, said tank having a chamber located. below said. electrodes, and mean for effecting passage of fluid from said chamber through said electrolyte.

18. In a fluid rheostat, the combination with an electrolyte tank, of a plurality of electrodes adapted to co-operate with the electrolyte therein, said tank having a chamber located below said electrodes, and means for supplying compressed air to said chamber, the latter having a plurality of reduced openings providing for escape of air therethrough. p

19. In a fluid rheostat, the combination with an electrolyte tank, of a plurality of electrodes adapted to co-operate with the electrolyte therein, said tank having a cham ber located below said electrodes, and means for supplying compressed air to said chamber, the latter having a plurality of reduced openings for permitting escape of air through the electrolyte adjacent said electrodes.

20. In a liquid rheostat, the combination with a plurality of electrodes, of means com prising a perforated member for effecting the passage of gas bubbles through the liquid.

21. In a liquid rheostat, the combination with a plurality of electrodes, of a perforated hollow member located below the electrodes, and means for forcing a gas throu h the perforations. I

22. n a liquid rheostat, the combination with a plurality of electrodes, of meansfor causing air bubbles to sweep upwardly past said electrodes.

In witness whereof, I have hereunto subscribed my name.

HENRY N. WADE. 

